Four people in the Trump administration have been charged for allegedly leaking classified information to the media.
The announcement was made Aug. 4 by Attorney General Jeff Sessions, Yahoo News reported.
Sessions did not confirm the identities of the individuals concerned.
"No one is entitled to surreptitiously fight their battles in the media by revealing sensitive government information," Sessions said, according to Yahoo.
In July, President Donald Trump criticized Sessions, saying that he had been weak in dealing with leakers. Sessions stated Aug. 4 that more than three times as many active investigations against leakers were currently under way than had been pending when the Obama administration left office in January 2017.
"No government can be effective when its leaders cannot discuss sensitive matters in confidence or talk freely in confidence with foreign leaders," Sessions added.
Transcripts of Trump phone conversations with the Mexican president and Australian prime minister were leaked to the press a day before Sessions' announcement.
"This nation must end the culture of leaks," he said.
The attorney general also issued a warning to other potential leakers.
"We will investigate and seek to bring criminals to justice," Sessions added. "We will not allow rogue anonymous sources with security clearances to sell out our country any longer."
White House counselor Kellyanne Conway suggested on Aug. 4 that lie detectors could be used to track down the sources of leaks.
News of the criminal proceedings came in the wake of the Aug. 3 report that special counsel Robert Mueller, who is overseeing the investigation into alleged Russian interference in the 2016 election, has appointed a grand jury.
A lawyer involved in the case stated on Aug. 4 that Mueller has two grand juries, one in Virginia and one in Washington D.C., according to USA Today.
Trump has continued to dismiss allegations of Russian involvement in the campaign.
"The Russia story is a total fabrication," Trump said at a rally Aug. 3, Yahoo reported. "It's just an excuse for the greatest loss in the history of American politics. That's all it is. It just makes them feel better when they have nothing else to talk about."
Trump's legal team had not been made aware prior to the announcement that a grand jury had been appointed.
"With respect to reports of a federal grand jury, I have no reason to believe that President Trump is being investigated," Trump attorney John Dowd said, according to USA Today.
Sources: Yahoo News, USA Today / Featured Image: U.S. Department of Justice/Wikimedia Commons / Embedded Images: U.S. Customs and border Protection/Wikimedia Commons, Sean Spicer/Wikimedia Commons